Method and device for depicting objects



April 7, 1942. 2,279,023

HARTMUT ISRAEL KALLMANN, FORMERLY KNOWN As HARTMUT KALLMANN ET AL METHODAND DEVICE FOR DEPICTING OBJECTS Filed Oct. 19, 1959 Patented Apr. 7,1942 I lTE STTES ATENT OFFICE METHOD AND DEVICE FOR DEPICTING OBJECTStion of Germany Berlin-Charlottenburg,

Application October 19, 1939, Serial No; 300,276 7 In Germany October19, 1938 15 Claims.

This invention relates to a method for the investigation of substanceswith the aid of quick neutrons and is particularly concerned with theprovision of means for showing the distribution of the intensity in abeam of quick neutrons.

It has already been suggested to show the dis-- tribution of theintensity in a beam of slow neutrons by first causing the slow neutronsto produce heavy particles, electrons or gamma rays in an intermediatelayer and then causing said heavy particles etc. to act upon afluorescent material or/and a photographic layer adjacent to the firstlayer. Showing the distribution of the intensity in a beam of slowneutrons is important especially when the neutrons are directed throughobjects, for instance, living bodies, in order to depict these objectswith the aid of slow neutrons.

Under certain circumstances the transillumination and depicting ofobjects by means of slow neutrons is however rather difiicult to becarried out especially if the objects investigated absorb slow neutronsparticularly strongly.

It is an object of the present invention to obviate these difficulties.Another object of the invention is the provision of means for showing arepresentation of the distribution of the intensity in a beam of quickneutrons. These inventive objects are attained by directing a beam ofquick neutrons through a body or substance and by causing the quickneutrons emerging from the body or substance to encounter anintermediate layer in which heavy particles, positively or negativelycharged electrons, or gamma radiation are produced under the action ofthe quick neutrons. These heavy particles etc. are in turn caused to actupon fluorescent material and/or a photosensitive plate or film adjacentto the intermediate reaction layer in the usual way. They thus produce arepresentation of the distribution of the intensity of the beam of quickneutrons on the fluorescent material and/or the photosensitive plate orfilm.

Showing a representation of the distribution of the intensity of a beamof quick neutrons is in general more complicated than showing arepresentation of a beam of slow neutrons due to the small power ofabsorption of the intermediate reaction layers against quick neutronsand due to their being necessarily rather thin in order to obtainsharpness of the images. The following layers are, however, well adaptedto the purpose in view. For instance a thin layer of paraflin can bemost adavntageously used in the following manner. The quick neutrons arecaused to liberate hydrogen nuclei from the layer of paraffin bycollisions, said nuclei emerging from the paraffin with high velocityare in turn caused to energize an adjacent fluorescent substance theradiation proceeding from which can be used for blackening aphotosensitive layer or for visual observation. Under certaincircumstances it is more favourable to cause the hydrogen nucleiemerging from the paraflin to act directly upon a photosensitive layer.Instead of the paraifin also other hydrogenous compounds can beemployed; finally also other atomic nuclei can be caused to be liberatedby the quick neutrons, but owing to their larger mass the transmissionof energy to these nuclei is much slighter than with hydrogen nuclei andin consequence thereof the output is very small.

The intermediate reaction layer may, furthermore, advantageously consistof a substance in which the quick neutrons produce nuclei disintegrationprocesses being accompanied by the emission of heavy charged particlesthese particles being causedto excite a fluorescent substance or/and toact directly or indirectly upon a photosensitive layer. Such reactionstake place for instance in magnesium or in layers containing this metal.

As intermediate reactions furthermore such nuclear reactions may beemployed in the course of which radioactive nuclei are generated underthe influence of the quick neutrons. These radioactive nuclei emitelectrons which can be in turn caused to energize fluorescent materialor/ and to act directly or indirectly upon a photosensitive layer.

As intermediate reaction finally all processes can be employed in thecourse of which excited nuclei are anyhow generated under the action ofthe quick neutrons. These excited nuclei give ofi" their energy ofexcitation, for instance in form of gamma radiation which can actdirectly or indirectly upon fluorescent material or/and a photosensitivelayer. As an example for such reaction we mention the excitation of thecadmium and copper nucleus by collision with quick neutrons. Thisprocess is distinguished by its comparatively large output.

Embodiments of the invention are illustrated in the accompanyingdrawing, in which Fig-1 is a perspective View, with parts broken away,of a device incorporating principles of the present invention, and

Figs. 2 and 3 are perspective views of modified forms of the deviceillustrated in Fig. 1.

In Figs. 1 and 2, I is a layer of paraflin 'or equivalent intermediatesubstance, and 2 is a layer .of fluorescent substance adjacent layer i.In. Fig. 2, 3 is a photosensitive layer adjacent layer 2 and on the sideof the latter remote from layer l. in Fig. 3, the layer of fluorescentsubstance shown at 2 in Fig. 2 is omitted, and the photosensitive layeris brought adjacent layer I.

We claim:

1. A method of obtaining an image of an object by means of quickneutrons, which comprises directing a beam of quick neutrons upon theobject, causing the emergent beam of quick neutrons to impinge upon alayer containing a substance which reacts with quick neutrons to emitradiation of the group consisting of charged particles and gammaradiation, and causing the radiation to impinge upon an adjacent layerof material which is sensitive to said radiation.

2. A method of obtaining an image of an object by means of quickneutrons, which comprises directing a beam of quick neutrons upon theobject, causing the emergent beam of quick neutrons to impinge upon alayer containing a substance which reacts with quick neutrons to emitradiation of the group consisting of charged particles and gammaradiation, and causing the radiation to impinge upon an adjacent layerof fluorescent material.

3. A method of obtaining an image of an object by means of quickneutrons, which comprises directing a beam of quick neutrons upon theobject, causing the emergent beam of quick neutrons to impinge upon alayer containing .a substance which reacts with quick neutrons to emitradiation of the group consisting of charged particles and gammaradiation, and causing the radiation to impinge upon an adjacent layerof photo-sensitive material.

4. A method of obtaining an image of an object by'means of quickneutrons, which comprises directing a beam of quick neutrons upon theobject, causing the emergent beam of quick neutrons to impinge upon alayer containing a substance which reacts with quick neutrons to emitradiation of the group consisting of charged particles and gammaradiation, causing the radiation to impinge upon an adjacent layer offluorescent material, and causing the resulting visible radiation toimpinge upon a photo-sensitive layer.

5. A device for forming an image of the distribution of the intensity ofa beam of quick neutrons, which comprises a front layer containing asubstance which reacts with quick neutrons to emit radiation of thegroup consisting of charged particles and gamma radiation, said frontlayer being immediately adjacent to a layer of material which issensitive to radiation emitted under the influence of quick neutrons.

6. A device for forming an image of the distribution of the intensity ofa beam of quick neutrons, which comprises a front layer containing .asubstance which reacts with quick neutrons to emit radiation of thegroup consisting of charged particles and gamma radiation, said frontlayer being immediately adjacent to a layer of fluorescent material.

'7. A device for forming an image of the distribution of the intensityof a beam of quick neutrons, which comprises a front layer containing asubstance which reacts with quick neutrons to emit radiation of thegroup consisting of charged particles and gamma radiation, said frontlayer being immediately adjacent to a layer of photo-sensitive material.

8. A device for forming an image of the distribution of the intensity ofa beam of quick neutrons, which comprises a front layer containing asubstance which reacts with quick neutrons to emit radiation of thegroup consisting of charged particles and gamma radiation, said frontlayer being immediately adjacent to a layer of fluorescent material, anda back layer of photo-sensitive material adjacent said fluorescentmaterial layer.

9. A device for forming an image of the distribution of the intensity ofa beam of quick neutrons, which comprises a front layer containing asubstance which reacts with quick neutrons to emit gamma radiation, saidfront layer being immediately adjacent to a layer of material which issensitive to gamma radiation.

10. The device defined in claim 9, in which the gamma radiation-emittingsubstance of the front layer is a metal of the group consisting ofcadmium and copper.

11. A device for forming an image of the distribution of the intensityof a beam of quick neutrons, which comprises a front layer containing ahydrocarbonaceous substance which reacts with quick neutrons to emithigh velocity hydrogen nuclei, said front layer being immediatelyadjacent to a layer of material which is sensitive to high velocityhydrogen nuclei.

12. A device for forming an image of the distribution of the intensityof a beam of quick neutrons, which comprises a front layer contain ingparaffin which reacts with quick neutrons to emit high velocity hydrogennuclei, said front layer being immediately adjacent to a material whichis sensitive to high velocity hydrogen nuclei.

13. A device for forming an image of the distribution of the intensityof a beam of quick neutrons, which comprises a front layer containing asubstance which reacts with quick neutrons to emit charged particles,said'front layer being immediately adjacent to a layer of material whichis sensitive to charged particles.

14. The device defined in claim 13, in which thecharged-particle-emitting substance is magnesium.

15. A method of obtaining an image of an object by means of quickneutrons, which comprises directing a beam of quick neutrons upon theobject, causing the emergent beam of quick neutrons to impinge upon alayer containing parafiin which reacts with quick neutrons to emit highvelocity hydrogen nuclei, and causing such emitted nuclei to impingeupon an adjacent layer of material which is sensitive to high velocityhydrogen nuclei.

HARTMUT ISRAEL KALLMANN, Formerly known as Hartmut Kall'mann.

ERNST-KUHN.

